PURPOSE: To supply power without using a wire from a distant place and to analyze a response signal from sensors or the like to which power is supplied in the distant plate.

CONSTITUTION: DC light λE sent from an optical transmission section 10 is accepted by an optical receiving section 30 through an optical fiber cable 20. A part of the received DC light λE is branched by a beam splitter 31 and supplied to an optical modulator 35. The other DC light λE is converted into the electric energy by a photoelectric transformer 32 and supplied to the optical modulator 35 and a piezo type distortion measurement device 34 as a driving power source. The response signal of the piezo type distortion measurement device 34 is sent to the optical modulator 35. The optical modulator 35 modulates the DC light λE branched by the beam splitter 31 in response to the response signal, then sends it as an optical modulation signal λE2' to an optical fiber cable 20, and sent to an optical transmission section 10.